PURPOSE: To extend the life of a sealing material and to decrease driving force of a shaft by enclosing the sealing material disposed on the outside circumferential part of the shaft by an elastic tube to retain axially the sealing material and providing a means for supplying a pressure fluid to the inside of the tube.

CONSTITUTION: A sealing material 29 and an elastic tube 17 are annularly disposed between an oscillating shaft 9 and a seal case 27 of a blast furnace device, etc. A pressure fluid source 25 is connected to the tube 17 and the fluid kept under adequate pressure is conducted via a regulating valve 23 to the tube 17 to pressurize the material 29 disposed on the outside circumference of the shaft 9. A sealing material retainer 18 and a sealing material retainer 28 in common use as a greasing ring are slid in grooves 19, 20. The material 29 in then press-fitted under the adequate pressure to the shaft 9 by the pressure fluid of a pressure fluid working part 26 in the tube 17 by which the high pressure gas in the furnace inside is sealed so as not to leak to the atm. side.